According to a recent trend of radiation therapy, in order to check an accurate position of a subject on which a treatment is to be carried out, such as a tumor, an image guided radiation therapy (IGRT) or respiratory gated radiation therapy (RGRT) technique is used. According to the IGRT, whenever the radiation therapy is performed, an image of a subject on which treatment is to be carried out, such as a tumor of the patient, is obtained using computed tomography (CT) equipment immediately before the radiation therapy. When a therapy plan is built, the obtained image is compared to re-adjust a position where the radiation is emitted, thereby securing accuracy of the therapy. Further, according to the RGRT, a real-time position management (RPM) system is used to track a position of a subject on which treatment is to be carried out, such as a tumor, in a chest or an abdomen, according to a respiration cycle of a patient and the radiation is emitted according to the movement of the tracked position.
The method for tracking a position of a subject on which treatment is to be carried out, such as a tumor, is mainly classified into two methods: The first method is a method of tracking a position by implanting a fiducial marker (or a gold marker) in a target. The first method has an advantage in that a movement displacement of the target is accurately checked, but also has a disadvantage in that the method is invasive and the target needs to be removed after performing the therapy. The second method is a method for tracking a position using an external marker. This method is non-invasive and may secure accuracy of target localization. However, in the related art, only one external marker is provided, which may lower accuracy of tracking a position.
According to Patent Document 1 (Korean Registered Patent No. 10-0943180), a biological signal is stabilized using training and relaxation response is provided to perform bio feedback. In the above-mentioned technologies, even though high tech equipment is used to correct the movement according to respiration of a patient, a cost therefor and training for every patient are uncertain. Further, a stability of a patient which has difficulty in breathing is lowered, so that a treatment time is increased. Specifically, a recent radiation technique transmits high dose intensity at once at a short treatment time so that movement of the patient, that is, a respiration amount needs to be indispensably considered.